1. Field of the Invention
This invention relates to a sulfonium salt and its manufacturing method and more particularly, to the sulfonium salt, represented by the following formula I including its manufacturing method, which is effectively used as a photoacid initiator or radical photoinitiator during polymerization and a photoacid generator leaving the protection groups of organic compounds.
Formula I ##STR1## in which, Ra, Rb and Rc are independently alkyl group, aryl group, allyl group, aromatic compound or benzyl group, respectively; n is an integer of 0 to 20.
2. Discussion of Related Art
In general , sulfonium salt is being effectively used as a photoacid initiator or radical photoinitiator during polymerization and a photoacid generator leaving the protection groups of organic compounds. Further, the sulfonium salt has been recently spotlighted as a photoacid generator of the chemically amplified photoresist, being employed in semiconductor materials.
According to the conventional method, it has been disclosed that the sulfonium salt is synthesized via two-step reaction in the presence of Grignard reagent (J. Am. Chem. Soc., 1990, 112, 6004-6015). Nevertheless, the conventional method recognized some disadvantages in that excess of Grignard reagent should be inevitably added in the two-step reaction and the full-scale industrial production has proven to be unavailable due to poor yield of final product.
Under the consideration of such a technological problem, further research has focused on the method of synthesizing the sulfonium salt via one-step reaction in the presence of trialkylsilyl triflate (J. Org. Chem., 1988, 53, 5571-5573). However, such method has failed to improve the poor yield related problem.